Why is social media's sibling comedy catching on?

"Have you guys seen the middle one? No?" says a young woman in a TikTok video — she's wearing TikTok's rudimentary "mom costume," a bathrobe and glasses. Impersonating a mother and pretending to address the other siblings, TikToker Khalessa Guevara uses a casual, indifferent tone. "I haven't seen her in a couple days. Do you guys have her number?"

In part of a TikTok video under the hashtag #siblings, Amanda McCants says: "No it's fine! Yell at me for something I did not do so I'll people-please later in life," presumably addressing parents.

And in another post with the title "Youngest child problems," 23-year-old TikToker Sam Perry lip-syncs a dramatic song as the text overhead reads: "Always being compared to my siblings and could never find myself as I was growing up … it's no surprise why I feel the need to be good at everything and set unrealistic, high expectations for myself."

Social media users seem to be fascinated with the idea of how birth order could both affect people's personality and how parents treat their children.

Found on virtually every social media platform are countless videos, graphics and memes talking about the perks and perils of being the eldest, middle or youngest sibling.

On TikTok alone, videos with hashtag #middlechildproblems have received at least 2.2 billion views. Certain accounts have garnered millions of followers by specializing in "sibling comedy," or making fun of how kids are treated differently by their parents based on the order of their birth.

Among viral videos are people who claim to be certified psychologists explaining a simplified version of Adlers' birth order theory — a theory that has not proven to be true.

Popular yet invalid

Alfred Adler, an Austrian psychotherapist, first came up with the birth order theory in the early 20th century.

According to the Alder institute in Mainz, Germany, the theory holds that the order in which a child is born shapes that person's development and personality.

A large part of social media content centered around the topic echoes how Adler categorized siblings: Firstborns tend to be responsible, authoritarian and under constant pressure to meet their parents' expectations; the middle one is typically forgotten; and the youngest is confident, fun-loving and wild.

This theory has inspired a pile of popular books since it was first propagated. But over the past decade or so, a spate of studies using large sample sizes and advanced statistical methods have discredited it.

Among these studies is one by Rodica Damian and Brent Roberts, who surveyed about 300,000 Americans. They found that birth order has no effect on personality traits. The results were echoed by other studies with large samples in the United Kingdom, Germany and other countries.

Although birth order can impact your life, such influences vary from a culture to culture or even family to family, Damian told DW, and do not create a visible, universal pattern in people's personalities.

Birth order could affect parenting

"Birth order can have an impact on your life if society pushes you in a certain direction based on cultural values, and if parents treat you differently based on such values," said Damian, who teaches social psychology at the university of Houston.

"For example, if culturally the firstborn child gets most of the family's resources, then they tend to become more influential members of their extended family in their adult lives."

While several studies hint that American firstborns tend to be slightly more educated that their siblings, Damian cited research conducted on an Indonesian sample that found the opposite result. "Later-borns in Indonesia tend to be more educated because the older children usually have to help their parents in farming or raising other siblings."

In the United States, the firstborn might be slightly overrepresented in higher education, "simply because the family's college money runs out for other kids," she pointed out.

Even if parents treat children differently based on their position in the family — which seems to be what most social media users are complaining about — other factors are more significant in shaping people's personalities, according to Damian.

"The types of friends you make as an adolescent, your peer group, is more important for your personality and development than your parents," she said.

"A firstborn child, for example, might be trained to be responsible but then they hit puberty, get in a group of delinquent friends and start doing risky behaviors."

"Your personality traits are often a result of genetics and a large set of life experiences combined, and birth order does not have any influential impact on it, directly or through parents," she said.

So why the fascination?

Despite evidence to the contrary, the public fascination with birth order has not abated. On the contrary, interest seems to be growing — particularly on social media platforms.

"I constantly get interviews from media sources being super interested birth order theory," Damian said. "Sometimes people even write me and say: 'You are wrong! We have children and we see these differences in their behavior!'"

For Christian Montag, a psychologist who studies social media, the popularity of invalid theories is typical to the medium.

"What we see in a lot of content and also behaviors online is that a lot of people don't want to do analytical thinking because this is effortful," he told DW. "It's rather easier to be reflective about things; to say, I only process what fits into my worldview."

Social media algorithms, many of which are kept secret, create virtual bubbles and echo chambers where people have contact only with content they like and confirm, said Montag.

In other words, when someone feels neglected in their childhood because that person was the middle child, there is a good chance that a constant flux of social media content with the same thrust will eventually turn that feeling into a conviction.

In addition, in today's digital world, kids prefer to talk about their problems online rather than confronting their families in person, Montag added.

Damian believes birth order theory enables us to do something very typical: blame others.

"It is often the easiest to blame things on your parents and your family."

A behavior that is universally human — despite our best intentions.

Edited by: Sonya Diehn